Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"substorms"”.
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MODELING OF PLASMA-SHEET CONVECTION: IMPLICATIONS FOR SUBSTORMS (MAGNETOSPHERE)
… to be released in sporadic events, namely substorms. It is shown that the idea of steady convection is inconsistent with the idea of slow, approximately lossless, plasma convection in a long, closed-field-line region that extends into a long magnetotail, such as occurs during Earthward …
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Ultra-Low Frequency Waves at Middle Latitudes During Substorms: Observations and Modeling
… Frequency (ULF) waves at middle latitudes during substorms. The dissertation consists of two major parts, observations and simulations. The research in this dissertation proposes that the main role in the generation of ULF waves at middle latitudes during substorm belongs to the plasmapause.</p> …
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Global Structure of the Nightside Proton Precipitation during Substorms using Simulations and Observations
… for the nightside proton precipitation. During substorms, the outflow from the near earth reconnection line at approximately 20 RE brings magnetic flux from the highly stretched magnetotail into the near earth magnetosphere. Once there, the flux piles up forming an azimuthally localized region …
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Statistical Study of Solar Wind Conditions Prior to Substorm Onsets
… past, studies have looked at small samples of substorms in order to make large-scale predictions. However in this study, a total of 28 years of solar wind data is analyzed from NASA’s OMNI database to determine if any predictions can be made at all. This thesis investigates statistical …
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Ionospheric Convection and Auroral Responses to Solar Wind Driving
… of solar wind driving and the auroral response. Substorms are a sporadic magnetospheric response mode, where the polar cap expands at first, followed by a distinct nightside brightening of the aurora and a decrease in polar cap flux. Steady magnetospheric convection events (SMCs) are times when …
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F-region Dusk Ion Temperature Spikes at the Equatorward Edge of the High Latitude Convection Region
… is at its strongest near the plasmapause during substorms. Another more likely possibility is that during substorms the region of sunward ion convection expands into a region in the evening side where the neutral gas moves in a direction opposite to the ions, thereby enhancing the frictional …
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Large-scale observations of the spatial and temporal dynamics of quiet-time Sub-auroral Polarization Streams using SuperDARN HF Radars
… such conjunctions between quiet-time SAPS and substorms to infer that quiettime SAPS were almost always associated with substorms and their durations were well bounded by that of the substorms for most cases. Next, we extend this analysis over to a statistical study of quiet-time and …
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Driving Influences of Ionospheric Electrodynamics at Mid- and High-Latitudes
… 5, we examined the external drivers of magnetic substorms using machine learning. We presented the first deep learning based approach to directly predict the onset of a magnetic substorm. The model has been trained and tested on a comprehensive list of onsets compiled between 1997 and 2017 and …
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Space- and ground-based observations of pulsating aurora
… pulsating aurora events and the relationship to substorms, to determine the altitude extent and precipitating electron distribution corresponding to pulsating aurora, and to understand commonly occurring features within pulsating aurora.</p>
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Empirical Study of Subauroral Polarization Streams (SAPS) through Decades of Satellite Observations
… well as the statistical variation of SAPS during substorms. Along with the qualitative results the statistics have revealed, the models allow for a more realistic SAPS electric field to be incorporated into a global convection model to study the effects of SAPS on the thermosphere and plasmasphere.
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Experimental study of current-driven turbulence during magnetic reconnection
… to power solar flares and magnetospheric substorms. Reconnection also controls the evolution of the topology of the magnetic field, enabling deleterious instabilities, such as the sawtooth instability in fusion experiments, to transport plasma across the experiment's minor radius. Notably, …
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Magnetic reconnection physics in the solar wind with Voyager 2
… processes such as stellar flares, magnetospheric substorms, and plasma accretion, yet it is poorly understood and difficult to observe in situ. In this thesis, the solar wind plasma permeating interplanetary space is treated as a laboratory for reconnection physics. I present an exhaustive …
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Experimental studies of magnetic reconnection in 3D geometries
… (solar flares), space (magnetospheric substorms), and laboratory settings (tokamak sawtooth oscillations). It allows for a change in the magnetic field topology in plasmas while also transferring the magnetic field energy to plasma energy. In return, the global magnetic field topology …
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Solar Wind-Magnetosphere Coupling: A Global Perspective of Reconnection in the Magnetotail
… of Events and Macroscale Interactions During Substorms (THEMIS) spacecraft earthward of the reconnection site, which was determined to be approximately -33 RE. Ground signatures indicative of substorm activity were also observed by the THEMIS ground-based observatories during this interval. …
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Effects of solar particle events on Geospace
… geomagnetic storms, cutoff latitude depression, substorms and polar cap absorption. The energetic proton populations of three selected SEP events from 2001 are used as 'tracers' to quantify the compression of the geomagnetic cavity during storm conditions. Empirical relations between the cutoff …
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The Study of Magnetotail Dynamics and their Ionospheric Signatures using Magnetohydrodynamic Simulation Model: OpenGGCM
… represent the onset of the tail reconnection and substorms in the ionosphere. To investigate signal propagation paths and signal travel times, single impulse or sinusoidal pulsations are launched at different locations of the plasmasheet, and the paths taken by the waves and the time that …
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Catastrophe Model for the Onset of Fast Magnetic Reconnection
Solar flares, magnetic substorms and sawtooth crashes in fusion devices are explosive events in which magnetic reconnection facilitates the rapid release of energy stored in stressed magnetic fields into the surrounding plasma. Much effort has gone into understanding how the energy is released so …
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Effects of ionospheric oxygen on magnetospheric structure and dynamics
… substorm simulation, the timing and strength of substorms are changed by a global O + outflow.
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Conductivity Modulation of Magnetosphere-Ionosphere Coupling
… solar eclipses are associated with geomagnetic substorms. All together, the research herein highlights the importance of considering ionospheric conductivity as a controlling parameter for magnetosphere-ionosphere coupling.
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A statistical study of plasmawaves and energetic particles in the outer magnetosphere
… of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft, Cluster mission, the Geostationary Operational Environment Satellites (GOES), Los Alamos National Laboratory (LANL) satellites, the Polar spacecraft and the Active Magnetospheric Particle Tracer Explorers …
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